Food production, particularly grain production is of increasing importance worldwide due to growing populations and other pressures such as reduction in arable land, climate change and the increasing use of crops for biofuel production.
Herbicides play an important role in modern agriculture by maximizing grain production, pasture production, quality and profitability. Herbicides allow undesirable plants to be killed or suppressed and thereby reduce competition with desirable plants such as crop plants for nutrients, water and the like.
Imidazolinone and sulphonylurea herbicides inhibit the growth and development of susceptible plants, including a wide range of weeds, by inhibiting the plant enzyme Acetohydroxy acid synthase (AHAS), also known as acetolactate synthase (ALS). AHAS synthesizes branch chain amino acids, a key function in plants. Importantly, imidazolinone and sulphonylurea herbicides also have relatively low toxicity to animals, including humans.
Imidazolinones include the following compounds imazethapyr, imazaquin, imazapyr, imazapic, imazamox and the like.
Commercially available imidazolinone herbicides include ON DUTY® (imazapic+imazapyr) INTERVIX® (imazamox+imazapyr) SPINNAKER® (imazethapyr), RAPTOR® (imazamox) and FLAME® (imazapic).
Although naturally occurring resistance to herbicides has been described in some crops many important food crops are susceptible to herbicides including imidazolinone.
Barley (Hordeum vulgare) is an important grain crop internationally because it is used in malt production, brewing and for human and animal feed. It has the advantage of being more salt tolerant than wheat and can be grown successfully on poorer quality land and/or in drier environments.
Weed control is a major issue in barley production. Good chemical weed control is desirable to maximize production of the crop and limit the need for mechanical cultivation and resultant damage to soil structure and erosion. In particular it would be desirable to utilize a greater range of low toxicity herbicides to control the full spectrum of a variety of weeds in a barley cropping system. For example, as most barley is resistant to sulphonylureas, this herbicide can be applied post emergence to growing barley crops, however, imidazolinones cannot be applied post emergence because barley is susceptible to this class of herbicides. Further, the crop cannot even be sown into soil containing imidazolinones because of its susceptibility to this herbicide.
The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art.